Method and apparatus for reporting buffer state by user equipment in communication system

Abstract

Provided is a method for reporting a buffer state by a user equipment accessing a first eNB and a second eNB in a communication system, the method comprising the steps of: triggering a buffer state report for new data when the new data is generated; selecting at least one eNB to which the buffer state report is to be transmitted, on the basis of the amount of uplink data to be transmitted; transmitting the buffer state report for the new data to the selected at least one eNB; receiving, from at least one eNB among the first eNB and the second eNB, a resource allocated by the at least one eNB as a response to the buffer state report; and transmitting the new data using the allocated resource.

The invention claimed is: 
     
       1. A method of reporting a buffer state by a user equipment (UE) connected to a first evolved node b (eNB) and a second eNB in a communication system, the method comprising:
 when new data is generated, triggering a buffer state report for the new data based on an amount of data stored in a buffer of the UE and at least one threshold value; 
 generating a random number and selecting at least one eNB of the first eNB and the second eNB that transmits the buffer state report based on a comparison result of the random number and a reference value and an amount of uplink data to be transmitted; 
 transmitting the buffer state report for the new data to the selected at least one eNB; 
 receiving a resource from at least one eNB of the first eNB and the second eNB in response to the buffer state report; and 
 transmitting the new data using the received resource. 
 
     
     
       2. The method as claimed in  claim 1 , wherein the triggering of the buffer state report for the new data comprises triggering the buffer state report for the new data when an amount of data obtained by excluding, from an amount of data reported in a previously transmitted buffer state report, an amount of data, which is allocated from the at least one eNB of the first eNB and the second eNB in response to the previously transmitted buffer state report, and an amount of data, which is possible to be transmitted is higher than the at least one threshold value. 
     
     
       3. The method as claimed in  claim 2 , wherein the selecting of the at least one eNB comprises determining the buffer state report to the first eNB when the amount of the data stored in the buffer of the UE is smaller than data throughput in each round trip time (RTT) based on a maximum transmission rate of the first eNB. 
     
     
       4. The method as claimed in  claim 1 , wherein the triggering of the buffer state report for the new data comprises triggering the buffer state report for the new data when the amount of the data stored in the buffer of the UE is larger than a first threshold value. 
     
     
       5. The method as claimed in  claim 4 , wherein the selecting of the at least one eNB comprises selecting both the first eNB and the second eNB when the amount of the data stored in the buffer of the UE is larger than the first threshold value. 
     
     
       6. The method as claimed in  claim 4 , wherein the selecting of the at least one eNB comprises selecting one eNB of the first eNB and the second eNB when the amount of the data stored in the buffer of the UE is smaller than a second threshold value. 
     
     
       7. An apparatus for reporting a buffer state by a user equipment (UE) connected to a first evolved node b (eNB) and a second eNB in a communication system, the apparatus comprising:
 a controller configured to,
 when new data is generated, trigger a buffer state report for the new data based on an amount of data stored in a buffer of the UE and at least one threshold value, 
 generate a random number, and 
 select at least one eNB of the first eNB and the second eNB that transmits the buffer state report based on a comparison result of the random number and a reference value and an amount of uplink data to be transmitted; and 
 
 a transceiver configured to transmit the buffer state report for the new data to the selected at least one eNB, receive a resource from at least one eNB of the first eNB and the second eNB in response to the buffer state report, and transmit the new data using the received resource. 
 
     
     
       8. The apparatus as claimed in  claim 7 , wherein the controller is further configured to trigger the buffer state report for the new data when an amount of data obtained by excluding, from an amount of data reported in a previously transmitted buffer state report, an amount of data, which is allocated from the at least one eNB of the first eNB and the second eNB in response to the previously transmitted buffer state report, and an amount data, which is possible to be transmitted is higher than the at least one threshold value. 
     
     
       9. The apparatus as claimed in  claim 8 , wherein the controller is further configured to determine the buffer state report to the first eNB when the amount of the data stored in the buffer of the UE is smaller than data throughput in each round trip time (RTT) based on a maximum transmission rate of the first eNB. 
     
     
       10. The apparatus as claimed in  claim 7 , wherein the controller is further configured to trigger the buffer state report for the new data when the amount of the data stored in the buffer of the UE is larger than a first threshold value. 
     
     
       11. The apparatus as claimed in  claim 10 , wherein the controller is configured to select both the first eNB and the second eNB when the amount of the data stored in the buffer of the UE is larger than the first threshold value. 
     
     
       12. The apparatus as claimed in  claim 10 , wherein the controller is configured to select one eNB of the first eNB and the second eNB when the amount of the data stored in the buffer of the UE is smaller than a second threshold value.